Heretofore it has been known that thermal shock-withstanding ceramic bodies can be made by impregnating a porous metal matrix with a ceramic compound which has a lower melting point than the metal. The importance of wetting the metal by the ceramic has been stressed (Grubel et al. U.S. Pat. Nos. 2,671,955 and 2,672,426). Furthermore, metals have been sintered together with lower melting conductive oxides to produce resistant contact surfaces (Ruben U.S. Pat. No. 2,200,854). This last mentioned patent stresses the importance of electrical conductivity in the oxide, and limits claims to the conductive vanadium pentoxide.
Ground glass (frit) and a noble metal have been mixed and fired as a film on a dielectric base to provide a resistor (as contrasted with an electric heating element (see Place et al. U.S. Pat. No. 2,950,995)).
Clay and molydenum or molybdic oxide particles, with a resin, have been extruded and fired to provide a heating element for use in a vacuum or reducing or neutral atmosphere (Navias U.S. Pat. No. 2,855,491).
In U.S. Pat. No. 2,924,540, D'Andrea has proposed a printable composition comprising a frit and silver and palladium and resin which may be first printed on a dielectric base and then fired to provide an electrical resistor element (as opposed to an electrical heating element).
Herbert in U.S. Pat. No. 2,946,937 has proposed an electrode composition wherein a metal in the form of a fine powder is mixed with a certain dielectric composition in the form of a fine powder and fired to produce a sintered electrode. At one point he states that any metal can be used which does not react with barium titanate or melt below 1150.degree. C. At another point he states that, "It is possible to produce electrodes by including any of the following elements in the dielectric composition, so that conductive particles are dispersed throughout the dielectric: copper, silver, gold, lead, antimony, bismuth, molybdenum, tungsten, iron, cobalt, nickel, ruthenium, rhodium, palladium, oxmium, iridium and platinum. If chromium or niobium are included in the composition then conductive oxides of these elements are formed." His second statement must be deemed to contain a clear error since iron indeed reacts with barium titanite and cannot be considered an equivalent of other metals included in the list which do not so react.